Object-c学习之路八（NSArray(数组)遍历和排序）

最新推荐文章于 2021-05-21 08:57:48 发布

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本文介绍了NSArray的四种遍历方法及三种排序方式，并通过具体示例展示了如何对包含Student对象的数组进行排序。

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今天学习了NSArray的遍历和排序，现在在这里做一下总结：

遍历现在实现了四中方法：

排序大概有三中方法：（代码中都有注释）

关于对象的排序还是以Student和Book为例每个Student持有一个Book.

主函数：

//
//  main.m
//  NSArray
//
//  Created by WildCat on 13-7-25.
//  Copyright (c) 2013年 wildcat. All rights reserved.
//

#import <Foundation/Foundation.h>
#import "Student.h"
#pragma mark 创建一个集合
void arrayTest(){
    //创建一个数组
    NSArray *array=[NSArray array];
    
    array=[NSArray arrayWithObjects:@"123",@"sf",@"dsg", nil];
    NSLog(@"array is:%@",array);

    NSLog(@"tength is: %zi",array.count);
}

#pragma mark 给数组里的元素发送消息
void arrayMessage(){
    Student *stu1=[Student student];
    Student *stu2=[Student student];
    Student *stu3=[Student student];
    NSArray *array=[NSArray  arrayWithObjects:stu1,stu2,stu3, nil];
    //让数组里的元素调用addMessage方法
    [array makeObjectsPerformSelector:@selector(addMessage:) withObject:@"你好。"];
 
}

#pragma mark 数组遍历(四种方法)

void arrayLoop(){

    
    Student *stu1=[Student student];
    NSArray *array=[NSArray arrayWithObjects:stu1,@"1",@"2",@"3", nil];
    //方法一   for循环
    for (int i=0; i<array.count; i++) {
        NSLog(@"%i->%@",i,[array objectAtIndex:i]);
    }
    
    //方法二
    int i=0;
    for (id obj in array) {
        NSLog(@"%i->%@",i,obj);
        i++;
    }
    //方法三   通过Block遍历：官方建议使用block
    [array enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
        NSLog(@"%zi->%@",idx,obj);
        //当执行到第3个时停止
        if (idx==2){
            *stop=YES;
        }
    }];
    
    //方法四 通过迭代器遍历
    
    //获得一个迭代器
    NSEnumerator *enumerator=[array objectEnumerator];
    id next=nil;
    while (next=[enumerator nextObject]) {
        NSLog(@"next->%@",next);
    }

    //反向遍历
    NSEnumerator *rvenumerator=[array reverseObjectEnumerator];
    id rvnext=nil;
    while (rvnext=[rvenumerator nextObject]) {
        NSLog(@"rvnext->%@",rvnext);
    }

    

}

#pragma mark 数组排序
void arraySort(){

    NSArray *array=[NSArray arrayWithObjects:@"4",@"1",@"2",@"3", nil];
    //排完后产生一个新的数组
    //指定元素的排序方法 compare:
    NSArray *array2=[array sortedArrayUsingSelector:@selector(compare:)];
    NSLog(@"排序后：%@",array2);
}
#pragma mark 对数组中的Student对象进行排序：
//先按照性进行排序，后按照名进行排序（两种方法）
void studentSort(){
    
    
    Student *stu1=[Student initWithFirstName:@"lianjie" LastName:@"Li"];
    Student *stu2=[Student initWithFirstName:@"dehua" LastName:@"Liu"];
    Student *stu3=[Student initWithFirstName:@"xingle" LastName:@"Li"];
    Student *stu4=[Student initWithFirstName:@"long" LastName:@"Cheng"];
    NSArray *array=[NSArray arrayWithObjects:stu1,stu2,stu3,stu4, nil];

    //第一种方法
    NSArray *array2=[array sortedArrayUsingSelector:@selector(compareStudent:)];
    NSLog(@"排序后：%@",array2);
    //第二种方法  通过Block排序
    NSArray *array3=[array sortedArrayUsingComparator:^NSComparisonResult(Student *obj1, Student *obj2) {
        
        //先按照性进行排序
        NSComparisonResult result=[obj1.lastname compare:obj2.lastname];
        //再按照名进行排序
        if (result==NSOrderedSame) {
            result=[obj1.firstname compare:obj2.firstname];
        }
        return result;

    }];
    NSLog(@"通过Block排序后：%@",array3);

}

#pragma mark 对数组中的Student对象进行排序：

//对数组中的Student对象进行排序：先按照性进行排序，后按照名进行排序（另一种方法）
void studentSort2(){
    
    
    Student *stu1=[Student initWithFirstName:@"lianjie" LastName:@"Li" bookName:@"book1"];
    Student *stu2=[Student initWithFirstName:@"dehua" LastName:@"Liu" bookName:@"book2"];
    Student *stu3=[Student initWithFirstName:@"xingle" LastName:@"Li" bookName:@"book2"];
    Student *stu4=[Student initWithFirstName:@"long" LastName:@"Cheng" bookName:@"book1"];
    NSArray *array=[NSArray arrayWithObjects:stu1,stu2,stu3,stu4, nil];
    //先按照书名进行排序
   
     NSSortDescriptor *bookNameDesc=[NSSortDescriptor sortDescriptorWithKey:@"book.name" ascending:YES];
     NSSortDescriptor *lastnameDesc=[NSSortDescriptor sortDescriptorWithKey:@"lastname" ascending:YES];
     NSSortDescriptor *firstnameDesc=[NSSortDescriptor sortDescriptorWithKey:@"firstname" ascending:YES];
   
    NSArray *decarray=[NSArray arrayWithObjects:bookNameDesc,lastnameDesc,firstnameDesc, nil];
    
    
    
    NSArray *array2=[array sortedArrayUsingDescriptors:decarray];
    NSLog(@"排序后：%@",array2);
    
      
}



int main(int argc, const char * argv[])
{

    @autoreleasepool {
       // arrayTest();
       // arrayMessage();
       //arrayLoop();
       // arraySort();
       // studentSort();
        //先根据book名，后根据性 ，再根据名 进行排序
        studentSort2();
    }
    return 0;
}

Student函数：

头文件：

//  Student.h
//  NSArray
//
//  Created by WildCat on 13-7-25.
//  Copyright (c) 2013年 wildcat. All rights reserved.
//

#import <Foundation/Foundation.h>
@class Book;
@interface Student : NSObject{
    NSString *_firstname;
    NSString *_lastname;

}
@property  (nonatomic,retain) NSString * firstname;
@property (nonatomic,retain) NSString * lastname;
//每个学生拥有一本书
@property (nonatomic,retain)Book *book;
+(id)initWithFirstName:(NSString *)firstname LastName:(NSString *)lastname;
+(id)initWithFirstName:(NSString *)firstname LastName:(NSString *)lastname bookName:(NSString *)bookName;
+(id)student;
-(void) addMessage:(NSString *)str;
-(NSComparisonResult)compareStudent:(Student *)stu;
@end

.m文件：

//
//  Student.m
//  NSArray
//
//  Created by WildCat on 13-7-25.
//  Copyright (c) 2013年 wildcat. All rights reserved.
//

#import "Student.h"
#import "Book.h"
@implementation Student
@synthesize firstname=_firstname;
@synthesize lastname=_lastname;
+(id)initWithFirstName:(NSString *)firstname LastName:(NSString *)lastname{
    Student *stu=[[[Student alloc] init] autorelease];

    stu.firstname=firstname;
    stu.lastname=lastname;
    return stu;
}
+(id)initWithFirstName:(NSString *)firstname LastName:(NSString *)lastname bookName:(NSString *)bookName{
    Student *stu=[Student initWithFirstName:firstname LastName:lastname];
    Book *book=[Book initBookWithName:bookName];
    stu.book=book;
    return stu;
}

+(id)student{

    return [[[Student alloc] init] autorelease];

}
-(void) addMessage:(NSString *)str{

    NSLog(@"%@->addMessage->%@",self,str);
}
-(void)dealloc{
    [_lastname release];
    [_firstname release];

    NSLog(@"%@ 被销毁",self);
    [super dealloc];
}
//定义一个排序方法
-(NSComparisonResult)compareStudent:(Student *)stu{
    
    
    //先按照性进行排序
    NSComparisonResult result=[self.lastname compare:stu.lastname];
    //再按照名进行排序
    if (result==NSOrderedSame) {
        result=[self.firstname compare:stu.firstname];
    }
    return result;
}
//重定义description 方法
-(NSString *)description{
    
    return [NSString stringWithFormat:@"%@ %@->%@",self.lastname,self.firstname,self.book.name];

}

@end

Book类：

.h文件：

//  Book.h
//  NSArray
//
//  Created by WildCat on 13-7-25.
//  Copyright (c) 2013年 wildcat. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface Book : NSObject
@property (nonatomic ,retain) NSString *name;
+(id)initBookWithName:(NSString *)name;

@end

.m文件：

#import "Book.h"

@implementation Book

+(id)initBookWithName:(NSString *)name{
    Book *book=[[[Book alloc] init] autorelease];
    book.name=name;
    return book;

}
-(void)dealloc{
    [_name release];
    [super dealloc];

}
@end